Bascule-bridge.



T. E. BROWN.

BASCULE BRIDGE.

APPLICATION FILED MAY 22. 1915.

Patented Nov,v 7, 19 16.

3 SHEETS-SHEET I /T\ i I i i i \i/ i T. E. BROWN.

BASCULE BRIDGE.

APPLICATION FILED. MAY 22. 1915.

Patented Nov. 7, 1916.

3 SHEETS-SHEET 2 E. BROWN. BAS CULE BRIDGE.

APPLLCATION FILED MAY 22. I9l5.

1,203,695. 1 Patented Nov. 7,1916.

3 SHEETS-SHEET 3.

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I 7 3 m. 7 gmvyy %mm 5? 3&1, (141011421 THOMASE. BROWN, OF NEW YORK, N. Y.

BASCULE-BRIDGE.

Specification of Letters Patent.

Patented Nov. 7, 1916.

Application filed May 22, 1915. Serial No. 29,815.

To all whom it may concern Be it known that I, THOMAS E. BROWN, a citizen of the United States, and a resident of the city of New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Bascule-Bridges, of which the following is a specification. v I

This invention relates to improvements in bascule bridges of the class wherein a counterweight is so connected with the bridge by rigging that the pull of the counterweight on the bridge automatically varies exactly as the turning moment of the bridge about its pivot varies, and thus the counterweight automatically balances the bridge in all its positions, notwithstanding that the turning moment of the bridge varies from one position to another of the bridge.

It is a purpose of the present invention to simplify and cheapen the construction and operation of such bridges, and particularly to elfect the raising and lowering of the bridge with the minimum expenditure of power and the secure holding of the bridge in its raised and its lowered position merely by means of simply constructed operating cables, weights and winding drums, and by simply pulling on a counterweight connection.

In my United States Patent No.. 1,151,657 dated August 31st, 1915, I have shown and described means to accomplish these results with two counterweights and two counterweight connections on each side of the bridge, and it is a special purpose of the present invention to produce these results with one counterweight on each side of the bridge.

The usual practice in bascule bridge construction is to use a single massive concrete weight extending across the bridge with connections at each side of the bridge, or to use separate massive weights on each side of the bridge and supported in the planes of the trusses, and I may use weights so arranged; but when such bridges are traversed by electric cars the towers must be abnormally high to avoid interference of a single cross weight with the trolley wires, and when massive weights supported in the plane of the trusses are used said weights hang over the roadway and cannot travel below the roadway level, and it is an object of my invention to so support the counterweights outside of the plane of the trusses and outside of the roadway that said counterweights will not interfere with the trolley wires or the roadway, and may descend below the level of the roadway.

Iprefer to use cables for the counterweight connections and hereafter use the word cable when referring to such a connection, although the connections may be constructed of chains, link bars or other suitable devices.

Referring to the drawings: Figure 1 is a s1de elevation of a bridge equipped with my said counterbalancing device. Fig. 2 is a side elevation of the bridge showing a special case of the application of my said invention. Fig. 3 is a broken rear view of the counterweight system, indicating the.

transverse girders X by solid lines in the upper part of said figure, and by dotted lines in the lower part of said figure. Fig. 4 is a broken side view of the counterweight arrangement shown in Fig. 3 and showing a portion of the supporting tower.

It will be understood that Figs. 1 and 2 show the counterbalancing devices for only one side of the bridge, but that generally in practice these devices will be duplicated, there being one set of-such devices for each side of the bridge. Therefore, in the description of said figures which follows reference is made to the devices on one side only, the corresponding parts on the other side of the bridge being similar to those described. i

Referring to Fig. 1, B is a bascule bridge; A A being the piers, P the pivot about which the bridge turns, Tthe tower; C the main counterweight cable, and C the secondary counterweightcable; S and S are the guide sheaves respectively for said ca- W is the counterweight. D is a winding drum for operating the secondary counterweight cable C; the letters 0. g. representing the position of the center of gravity of the bridge; the weight of said counterweight Wis preferably just sufficient to balance said bascule bridge when the latter is in its lowest position, and it will be evident that by rotating said drum D by any suitable power in the proper direction said bridge B.will be raised or lowered. The secondary counterweight cable 0 is attached to some suitable point of the bridge, substantially distant from said pivot P, as the elbow of the upper chord f, and said the pull of the cable C becomes opposed in.

primary cable C passes around a saddle F and is fastened to said bridge at some point back of said saddle F and preferably at the pivot B; said saddle forming a curved way or guide on which said cable G is laid. Said saddle F is secured preferably to the upper side of the bridge as shown by any suitable framing such as the post and the tie rods 25 Z. hanger H supporting said counterweight V, the main and secondary counterweight cables 0 and C being attached at opposite.

ends of said lever L. By suitably locating the position of the fulcrum I on said lever L, the weight W may be distributed in any desired proportion on the said cables C and C. X are transverse girders supporting the counterweight W. 7

As the bridge rises to differentpositions the cable C unwraps from said saddle F, said cable forming the tangent of the curve. The curve of the face of said saddle F on which the said cable C is laid is formed so that the sum of the moments of the cables 0 and C around the pivot P of the bridge will equal the moment of the bridge around said pivot P, as described in my United States Patent, No. 1,151,657, dated August 31st, 1915, and in accordance with the formula given in said patent, namely,

in which formula in this case W and l/V represent the amount of the portion of the counterweight lV carried by the primary cable C and secondary cable C respectively, and Z and Z represent lever arms of said cables respectively about the pivot P. vB represents the weight of the bridge, R the radius from the pivot P to the said center of'gravity '(0. g.) of the bridge and a the angle which said radius makes with the horizontal. v

To effect the control of the bridge the point of attachment f of said secondary cable C is preferably so chosen that the lever arm of said cable C is always of substantial length, and therefore the moment W"Z will always be a substantial quantity; therefore, asthe bridge rises and the angle or increases its cosine diminishes and the right hand member of the equation becomes less and less, until at some point between the vertical and horizontal positions of the bridge, it equals WZ and the term Vi then becomes equal to Zero,c'. 6., Z must then be equal to zero, and the line of the cable C then passes through the pivot P in this position of the bridge. As the-bridge continues its upward motion the termWVZ becomes negative, and

its effect on the bridge to the pull of the cable C, and thus an eflicient and simple means of operating and controlling the bridge by cable O is provided. Moreover,

L is a lever pivotally attached to the 0nd reverse saddle F is therefore preferably used to effect the aforesaid opposition to the pull of the cable C to complete the balance during the remaining upward motion of the bridge. If the point of attachment of the said cable C to the bridge is placed high enough above the pivot P a sin gle curve F can be used, and the said reverse curve F may be dispensed with, but this usually necessitates the use of otherwlse superfluous structural. members, and I prefer to use the reverse curve F.

The bridge being balanced in all its positions by the combined tensions of the cable connections C and C, it is manifest that with a pull on the cable C in either direction the balance will be destroyedand I accomplish suchpull by attaching the secondary cable C to a winding drum D, and thus when said drum D, arranged as in Fig. 1, is revolved in the direction of the hands of a cloclqthe bridgerises and when re volved in the reverse direction the bridge descends. Said drum D may be revolved by any suitable means, as by gear Grand pinion 9 on shaft 6, said shaft '6 being revolved by any suitable motive power, such as a steam or gas engine or electric motor, and suitable brakes should be provided for stopping the motion of the said drum D1 Obviously the power to lift the bridge is only limited to the power available to operate the drum D and the strength of the cable C; but the maximum power in lowering the bridge is attained when the torque of drum D equals the proportion of the counterweight supported by the cable C: hence the proportion of the weight V supported onthe cable 6' must be sufiiciently great that the moment of said cable C shall exceed the greatest moment that can be produced by wind pressure and friction on the bridge at the greatest wind pressure against which it is intended that the bridge shall be operated. This condition governs the amount of the portion of the weight JV whlch' must b'e carried onthe operating cable C and therefore determines the ratio of the arms of't'he lever L. The length of the arms of the lever 7L, while conforming to thisratio, must be sufficient to provide for the differences of movement of the two connections C and C. which not only do not when the conditions are such that it is desirable that the tension of the cables 0 and C shall be equal. In this case, instead of attaching the cables C and C to the lever L, and placing the fulcrum I in the center of said lever so as to make a lever of equal arms, we may omit said lever L and place on the pivot of hanger H a sheave wheel K which is the equivalent of a lever of equal arms, and which enables me to use a continuous cable for both parts G and C instead of the separate cables as shown in Fig. 1. The operation of Fig. 2 is obviously the same as described for Fig. 1.

Referring to Figs. 3 and 4; Fig. 3 is a view looking lengthwise of the bridge, with the lower parts of the tower T removed for the sake of clearness, and showing the counterweights and their supports and a section across the roadway, and Fig. 4 is a side view showing a portion of the tower and a counterweight and connections. S and S are the leading sheaves for the primary and secondary cables C and C respectively, L the levers, I their fulcrums and H hangers, all substantially as hereinbefore described for Fig. 1. X are transverse girders supporting the weights W by means of the hangers H, said girders in turn being supported on the cables C and C by means of the levers L. 2 are trolley wires, 1 are the curbs along the roadway, 5 are pits outside of the roadway into which the weights W descend, 6 are wire guards for said pits, 1 being the ends of the trusses and 3 the portal strut of the bridge as they would appear with the tower removed.

In Fig. 1 the levers are shown in the plane of the trusses, z. e. in the same plane as the cables G to more clearly show the principles of the invention, and this ar rangement is useful when the weights are placed in the planes of the trusses, or when a single cross weight is used, but when the roadway so that the trolley wires and roadway are not interfered with and do not limit the travel of the counterweights is clearly shown by Fig. 3.

New having described my invention, I claim l. The combination in a movable bridge of counterweights, counterweight connections and a girder supporting said counterweights on said connections, said girder being extended beyond the planes of the trusses and having the points of support of said counterweights outside of the planes of the trusses of said bridge.

2. The combination with a movable bridge of counterweights, counterweight connections descending over the roadway, and a transverse girder having its ends extended beyond the roadway and supporting said counterweights outside of the roadway of said bridge.

3. The combination with a movable bridge of counterweights adapted to balance said bridge, counterweight connections in the planes of the trusses and over the roadway and a transverse girder extended beyond the planes of the trusses and supporting said counterweights outside of the roadway of said bridge.

Signed at New York city, in the county of New York and State of New York this nineteenth day of May, A. D. 1915.

THOMAS E. BROWN.

Witnesses:

BAcHn H. BROWN, CARL T. WESTLIN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

